The systems and techniques described herein relate generally to wiring system monitoring and diagnostics. More specifically, they relate to partial discharge monitoring for detecting faults, such as chafing, in wiring harnesses.
A wiring harness is a group of wires that are bundled together in order to simplify their handling and routing. Although bundling wires together into a group makes the process of handling them collectively easier, it also makes inspection and repair of individual wires within the bundle more difficult. In addition, because the wires are bundles together, the wires in a harness are subject to rubbing and chafing during vibration or other physical loading, which can lead to degradation in the wire, and ultimately a loss of performance. The problem is especially significant in high-vibration environments, such as helicopters.
Monitoring the wires within a bundled harness is desirable to detect faults as they develop, and before they become severe enough that the signal being carried by a wire is lost entirely. Various techniques have been used, including visual inspection, impedance testing, and reflectometry. However, each of these has limitations. For instance, in many circumstances, such as within an aircraft, much of the wiring is not available for visual inspection without significantly dismantling the harnesses. Impedance testing requires connecting and disconnecting wires in order to attach them to the testing system. Reflectometry, which involves sending a pulse down a wire and then studying the peaks and waves of its reflection as it returns, is an effective technique, but is generally less able to detect developing problems while their magnitude is still small. In effect, chafing and fraying is not effectively detected by such techniques.
Because of these and other limitations of existing monitoring technologies, there is a continuing need for improved systems for detecting and localizing wiring defects, such as chafing.